Some sources describe ambergris as a product of illness in the whale; Melville blames it on indigestion. However it is now believed that ambergris may serve a useful purpose in protecting the intestines of the sperm whale from the stings or sharp beak of the giant squid, which form the major part of its diet. Ambergris is either extracted from the dead body of the whale (as is recounted in Moby-Dick), or found floating on the sea or washed up on a beach.

A substance of the consistence of wax, found floating in the Indian Ocean and other parts of the tropics, and also as a morbid secretion in the intestines of the sperm whale (Physeter macrocephalus), which is believed to be in all cases its true origin. In color it is white, ash-gray, yellow, or black, and often variegated like marble. The floating masses are sometimes from sixty to two hundred and twenty-five pounds in weight. It is wholly volatilized as a white vapor at 212° Fahrenheit, and is highly valued in perfumery.